Enhanced 911 (i.e., E911 or E-911) systems link emergency callers with appropriate public resources using an easy access code. The easy access code used throughout North America, for example, is 911. In most cases, a person in an emergency situation dials 911 to make a voice call to a public safety answering point (PSAP), although some PSAPs now support 911 text messaging as well. In order to provide emergency assistance to a caller, the E911 system attempts to associate a call with a location of the call. The location may be a physical address or other geographic reference information. The E911 system may use the caller's telephone number in various ways to identify a location that can be used to dispatch police, fire, emergency medical, and other response resources to the caller. Identifying the location of the emergency is especially helpful in situations when it may be difficult to communicate one's location, for example, during fires, break-ins, kidnappings, and other emergency events.
For a 911 call from a fixed landline, e.g. from a residence, the location determination usually entails a translation of telephone number data for the calling party's line into the calling location address (e.g. the address of the caller's residence). Effectively identifying the location of a mobile-originated call, however, presents difficulties not present in determination of location of a caller from a landline. When a mobile-originated call is made, for example, the E911 system may acquire the location of a cell tower to which the mobile device is connected. The location of the cell tower, however, may correspond to a radio coverage (cell) area of 10 to 100 square miles. Thus, precisely locating a caller within such a large area may prove difficult, or even impossible. To better assist locating mobile-originated callers, the E911 system may also attempt to obtain a more accurate position of the caller, for example, by using GPS and/or trilateration from some number of cell towers. Although this process may result in a more precise location of the caller, locating the caller using GPS and/or cell tower trilateration may take relatively long periods of time. For example, especially long periods of time may be required if the mobile terminal must initiate an initial position fix by syncing with GPS satellites, and/or the mobile device has to communicate with network-based systems that assist in position determination.
This disclosure focuses on E911 for fixed wireless devices. Fixed wireless devices are devices that communicate over a wireless network, similar to traditional mobile devices. Unlike traditional mobile devices, however, fixed wireless devices are immobile in nature. Fixed wireless devices, for example, may be situated in relatively fixed locations (e.g., such as installed at a home or office) during use for at least substantial periods. Despite being situated in relatively fixed locations, conventional fixed wireless devices operate with the same functionality and limitations associated with traditional mobile devices. For example, conventional fixed wireless devices suffer from limitations in effectively determining locations similar to those encountered in attempting to determine the location of mobile devices. Such limitations include the unreliable and/or inefficient identification of a location of a fixed wireless device that has made a 911 call.